Amazon FBA profit calculator — net margin per unit
Most FBA sellers track gross margin (sale minus COGS). Real profit is what you keep after referral fees, FBA fulfillment, inbound shipping, and PPC per unit.
Profit formula (per unit)
Net profit = Sale price − COGS − Inbound ship − Referral fee − FBA fee − Ad spend per unit
Referral % varies by category (often 8–15%). FBA pick & pack depends on size/weight tier. Storage, returns, and remission are separate — budget those before scaling inventory.
Example: $29.99 kitchen gadget
$29.99 sale · $6 COGS · $0 outbound (FBA ships) · ~$4.50 referral + FBA stack · $4 PPC CPA → net ≈ $15.50/unit (52%), not the 80% gross margin COGS alone suggests.
At 300 units/month that's $4,650 contribution — if net drops under $5/unit, scaling ads scales losses.
When margin % matters most
- Reorder decisions — run real COGS + inbound before placing PO
- PPC scaling — if TACoS is 25%, that's a quarter of revenue gone
- Category moves — referral % jumps between Home (15%) and Electronics (8%)
When to upgrade from a calculator
At 3,000+ orders/month, Sellerboard ($19+/mo) syncs Amazon fees and inventory automatically. Until then, fast what-if FBA math is enough.
Open Amazon FBA calculator →